Flat panel electronic devices, including tablet PCs, flat panel mobile phones, etc., are widely used as audio playing apparatuses because of advantages, such as portable characteristic, fashion and multifunction. In the prior art, a pair of speakers which are disposed at the left side and right side of the flat panel electronic device are usually used for playing the left channel audio and the right channel audio corresponding to the left ear and the right ear respectively, so that a user can experience the stereo effect. However, in use, the flat panel electronic device is often be rotated by the user according to actual requirement. The rotations of the flat panel electronic device result in changes of the positions of the speakers. For example, the initial left-and-right arrangement of the speakers changes into the top-and-bottom arrangement as the flat panel electronic device is rotated by 90° or 270°. The audio enjoyment of the user is inevitably affected when the left channel audio and the right channel audio are played from the top and the bottom of the flat panel electronic device, respectively. Even though, the rotation of 180° of the flat panel electronic device results that the left channel audio and the right channel audio are played from the right side and the left side of the flat panel electronic device, respectively, thus it will also affect the audio enjoyment of the user.